The invention relates to an arrangement for measuring the range or speed of an object, wherein two optical devices are provided, which are offset relative to one another approximately transversely to the direction of the object, and which supply two images of the object, which images are in the form of electrical signals, and by a comparison of the signals, forms a measured value which represents the range.
An arrangement of the type wherein two images are derived from two subsidiary pupillary openings which represents partial areas of the entrance pupil of an objective lens system, and wherein the light entering the respective openings are supplied to separate photo detectors, is described in German AS No. 2,156,617, with particular reference to FIG. 2 thereof.
The disadvantage of this known arrangement resides in the fact that each of the photo detectors supplies an electrical signal which is derived from an integration of the brightness values of the overall image content. The congruency of two images obtained by a comparison of two such signals cannot be established with a high degree of accuracy. Moreover, the two images are derived over a grid which is arranged in an image plane of the object and is mobile within the latter, which increases the mechanical outlay. Further, the distance of the object is not established until after a focusing procedure of the objective lens system from the mechanical setting of the latter.
The present invention therefore has among its objects the improvement upon known arrangement, of the general type referred, to with respect to the measuring accuracy which can be achieved, at the same time providing the simplest possible design arrangement.
This is achieved, in accordance with the invention, by an arrangement in which two optical devices are provided which are offset from one another transversely to the direction of the object and which supply two auxiliary images of the object, and wherein a device is provided with analyses of the images, in the form of electrical signals, and, by a comparing of signals, forms a measured value which represents the range. One of the two optical devices includes a rotatably mounted mirror or reflector which is adapted to be rotated by a setting device in a sequence of settings, with the analyzing device containing two CTD image sensors individually assigned to the images and having linearly aligned image points arranged, in parallel relation, in the displacement direction of the image derived from the rotatably mounted reflector. The read-out signals obtained are supplied to an evaluating circuit which, on the occurrence of a sequence of read-out signals from the two image sensors, assigned to the setting sequence, forms from the difference therebetween a sequence of read-out signals integrated over the image points, and provides an output signal, dependent upon the setting of the reflector, on the occurrence of the integrated read-out signal having the smallest amplitude, which is representative of the range of the object.
In accordance with another feature of the invention, two optical devices are provided which are offset relative to one another at right angles to the optical axis, and which supply two auxiliary images, both of which are normally stationary, and two CTD image sensors are provided which are associated with the respective optical devices, the auxiliary images being generally displaced relative to one another, with their image points being linearly aligned and arranged, in parallel relation, in the direction of mutual displacement of the auxiliary images. The output of one of such image sensors is connected directly, or over a constant delay element, to an evaluating circuit and the output of the other sensor is connected to the evaluating circuit over a delay element which can be adjusted in a stepped manner in a predetermined setting sequence. The read-out signals obtained are suitably processed to provide an output signal which is characteristic of the delay set upon occurrence of the integrated read-out signal having the smallest amplitude, which is representative of the range of the object.
In accordance with another feature of the invention two optical devices are provided, which are offset relative to one another at right angles to the optical axis, and supply two auxiliary images, and two CTD image sensors are provided which are associated with the respective optical devices, the auxiliary images being generally displaced relative to one another, with their image points being linearly aligned and arranged, in parallel relation, in the direction of mutual displacement of the auxiliary images. The output of one of such image sensors is connected to a delay line having a plurality mutually offset outputs, and a series of differential amplifiers are provided whose first inputs are connected to respective outputs of the delay line, and whose second inputs are connected to the other image sensor either directly or over a constant delay element, with the outputs of the amplifiers being connected over respective rectifiers and respective following integrators to the inputs of a second evaluating circuit which determines the integration having the smallest output signal and produces signal which is characteristic of such integration and is representative of the range of the object.
The present invention has the particular advantage that the congruency of the two images is established by means of the correspondence or conformity of two electrical signals which are respectively obtained merely by integrating the brightness values prevailing in one line of the relevant image. This substantially increases the accuracy in the establishment of congruency, as compared with known arrangements. In particular, an erroneous measurement which could be caused by a random agreement of the signals, integrated from the entire image contents, without congruency actually existing between the two images, is eliminated. A further advantage resides in the fact that the CTD image sensors can be monolithically integrated on a semiconductor substrate with the individual components of the analyzing device forming a semiconductor module which can be easily accommodated in various devices which employ measurement of this type, without noticeably increasing the space requirement.